Green Cobra Female Guppy (Poecilia reticulata)

Meet the Green Cobra Female Guppy

The Green Cobra Female Guppy is a domestic colour form of the guppy, Poecilia reticulata, a livebearing fish in the family Poeciliidae. FishBase records its native range as Venezuela, Barbados, Trinidad, northern Brazil and the Guianas. This female form reaches 5 cm standard length and suits a prepared beginner who can provide a mature filtered aquarium, stable mineral-bearing water, companionship and a plan for possible fry.

The accepted scientific name remains Poecilia reticulata, as listed by Eschmeyer’s Catalog of Fishes. Green Cobra is a selected trade-form description rather than a separate species or wild locality. Domestic colour forms can vary between individuals, so build the care plan around the species and the female adult size rather than one particular pattern.

Our complete Guppy Care Guide classifies guppies as easy for a prepared keeper, not as maintenance-free fish. A suitable keeper tests water, maintains the filter, plans a social group and responds when one fish hides, misses food or receives persistent attention. A newly filled aquarium, an isolated display or an aquarium selected only by litres does not meet that standard.

Decisive planning figures

• Adult size: plan for a female reaching 5 cm standard length.
• Social plan: keep five or more where aquarium capacity and the sex plan allow.
• Aquarium: use a mature filtered aquarium at least 60 cm long for one small group.
• Routine water: keep 22–28°C, pH 7.0–8.0 and 9–18 dGH.
• Temperament: peaceful, but vulnerable to fish that nip fins.

Understand the female offer and gallery

One purchase supplies one Green Cobra Female Guppy. The dispatch size is approximately 3–4 cm, which describes the fish at dispatch rather than its final size, age or reproductive history. Plan the aquarium for a 5 cm adult female and the needs of the complete social group from the beginning.

Sex is guaranteed only when the exact product or selected option explicitly states male or female. This Green Cobra Female Guppy listing is sold as female. Female guppies are generally larger and plumper than males, and the male has a narrow modified anal fin called a gonopodium. Domestic females can still carry strong colour, so colour alone is not a dependable way to distinguish the sexes.

This is one fish rather than a pair, trio or breeding group. Ordering several individual fish does not establish parentage, a balanced mixed-sex ratio or a particular reproductive outcome. If the aquarium will contain males, keep two females to each male, as OATA advises, with enough space, filtration and cover for every adult.

The gallery images are representative of this type of animal rather than photographs of the exact animal supplied, so colours can look slightly different from the live animal. The first image shows a silver-green fish with black-spotted yellow-green fins against a blurred background. The second shows a metallic green and grey fish above gravel, with plants and wood behind it. Those visible details describe the gallery scenes and do not promise identical markings on an individual fish.

The trade form can be compared with other guppies through the current guppy collection. Check the sex, sale unit and form named on each guppy before adding it to the group.

Decide whether this guppy suits your aquarium

This fish suits a keeper with a mature aquarium at least 60 cm long, measured water within the routine range and space for a social group of five or more. It can be a good first tropical species when the aquarium has been cycled before the fish arrives and the keeper is ready to test ammonia and nitrite, feed controlled portions and complete regular partial water changes.

Choose another plan if the aquarium is an unfiltered container, if it cannot support the full adult group, or if its residents are known fin nippers. A female-only group prevents new mating within that group, but a female may retain sperm after an earlier encounter with a male and later produce young. Population capacity and responsible rehoming therefore belong in the plan even when no male is being added.

Do not use a fish-per-litre formula to decide capacity. The same nominal volume can have a different length, footprint, mature filtration, existing livestock and usable swimming room. Check the complete adult group, water test results, behaviour and feeding access before increasing the population.

Plan the aquarium around the adult female size

Plan for an adult female reaching 5 cm standard length. Standard length excludes the tail fin, and domestic tail length varies between fish. Use the 5 cm adult figure throughout the aquarium plan so the dispatch-size fish is never treated as a permanent nano fish.

Seriously Fish gives a species-level minimum footprint of 45 × 30 cm and approximately 41 litres. Tropical Fish Co applies a more conservative house screen of a mature aquarium at least 60 cm long for one small group. OATA’s 45-litre figure applies to a small group of smaller livebearers, while litres alone cannot account for length, sex mix, tank mates, filtration or possible fry.

Work through the aquarium decision

A conventional 60-litre aquarium can be a candidate when it is at least about 60 cm long, mature, filtered, suitably furnished and not already fully occupied. Five guppies are a conservative starting group under our policy, not an automatic maximum. Existing fish, a mixed-sex plan, retained fry or weak biological filtration can make the same aquarium unsuitable.

More water can improve stability and provide additional layout choices, but volume does not remove the need to test water or observe the group. Persistent pursuit, missed feeding, fin damage or a rising nitrate trend means the plan needs intervention rather than another fish.

Build a mature, filtered home with swimming room

Use a biologically mature filter, open swimming room, cover and areas where a fish can move out of another’s line of sight. The RSPCA explains that biological filtration supports bacteria that convert toxic ammonia into nitrite and then safer nitrate. Clear water does not show whether that process is working, so test results must confirm the aquarium is ready.

If this is your first setup, prepare and mature it before livestock arrives by following the first tropical aquarium guide. Running equipment for a few days is not the same as establishing enough bacteria to process fish waste. Add livestock slowly because feeding and additional fish increase the load placed on the filter.

Arrange the usable space

• Open water: preserve a clear horizontal route for normal group movement.
• Cover: use live plants where practical, or smooth artificial plants and suitable ornaments.
• Flow: avoid a strong current that continually pushes the fish or prevents normal swimming.
• Refuge: create sight breaks without filling every part of the aquarium with decoration.
• Separation: keep a mature alternative space ready if persistent pursuit or illness makes isolation necessary.

Seriously Fish describes the species as unfussy and notes that planted aquaria with floating vegetation are appreciated. Plants and cover are useful only when the fish can still move and feed normally. Dense planting can also allow more fry to survive, so every increase in shelter should be considered alongside the population plan.

Check that the filter intake cannot trap small fish or fry and that the return does not pin the group into one area. Observe the fish rather than judging flow by the filter setting alone. A suitable current lets each fish hold position, cross the aquarium and reach food without continual effort.

Keep water inside the shared routine range

Keep the aquarium at 22–28°C, pH 7.0–8.0 and 9–18 dGH. These figures are the overlap of the Tropical Fish Co routine range with FishBase, Seriously Fish and OATA. OATA’s guppy-and-molly sheet is group guidance, while the other ranges keep the routine values within the species’ recorded limits.

Maintain ammonia at 0 mg/L and nitrite at 0 mg/L. OATA advises nitrate no more than 20 mg/L above the normal level in the tap water used for changes. Test both the source water and aquarium because UK supplies differ and can change. Record the readings so a rising trend is visible before fish show signs of distress.

The water chemistry guide explains what each reading means. Compare measured aquarium values with the target through the water matcher, then judge every proposed resident against the same temperature, pH and hardness range.

Do not add salt simply because wild guppies can occur in brackish water. A routine freshwater aquarium should remain freshwater unless there is a measured purpose that is safe for every fish, plant and invertebrate. Salt cannot replace mineral content, mature filtration, testing or water changes.

Feed a complete staple that fits the recorded diet

Use an appropriately sized, nutritionally complete omnivore flake or granule as the staple, with safe invertebrate and algal variety. FishBase records zooplankton, small insects and detritus in the wild diet, while Seriously Fish describes wild fish as primarily insectivorous and notes that domestic aquarium fish accept most foods offered. The main food should therefore be a complete preparation supported by small animal-based variety rather than one treat food.

OATA advises feeding once a day and offering only what the fish can consume within a few minutes. Offer a controlled daily ration that leaves no food to decay. Distribute small particles across more than one point and watch that every fish feeds.

Build a practical rotation

A fish that repeatedly misses food may be displaced, stressed or unwell. Spread the ration, check whether another fish is pursuing it and inspect its breathing, fins and swimming. Do not compensate by adding large amounts that the rest of the group leaves behind.

Uneaten food increases the waste processed by the filter and can contribute to ammonia, nitrite or nitrate problems. Remove leftovers and reduce the next portion. Use foods intended for aquarium fish and store them as directed so the routine remains consistent and biosecure.

Fry require food small enough for their mouths and particularly close water-quality monitoring. Their presence also changes the aquarium’s total feeding and filtration load, so count surviving young in the maintenance plan rather than continuing the adult ration unchanged.

Plan the social group, sex mix and possible fry

Keep five or more guppies where aquarium capacity and the sex plan allow. FishBase gives an aquarium group of five or more, while OATA advises at least three. Tropical Fish Co uses the more conservative five-plus policy because companionship must be considered alongside adult size, filtration, water tests and every other resident.

For a mixed-sex group, OATA advises two females to each male, and Seriously Fish advises several females to each male because males can be vigorous in their constant pursuit of females. This ratio is meant to reduce stress on females, but it does not prevent breeding or guarantee that every fish can feed and rest. Watch individuals for repeated pursuit, cornering, hiding, missed meals or fin damage and keep a mature separation option ready.

Seriously Fish states that females can retain viable sperm and produce young after males are absent. A female-only purchase therefore cannot be treated as a promise that fry will never appear. Decide in advance whether young could be housed responsibly or rehomed.

Guppies are livebearers. Adult guppies will eat the young, while dense planting with plenty of floating vegetation gives fry the best chance of survival. Do not use predation as a population-management plan. If young are deliberately retained, use mature biological filtration, stable suitable water and repeated tests for zero ammonia and nitrite.

Trade-form wording does not establish the sire or guarantee how offspring will look. Keep documented lines apart, and do not represent descendants as a pure colour line without controlled parentage.

Maintain the filter and respond to health changes

Change 25% of the aquarium water at least once every week. Treat replacement tap water with conditioner before adding it, siphon settled waste and check the filter for blockages.

When filter media needs cleaning, rinse it lightly in aquarium water removed during the partial change. Do not rinse it under the tap. Avoid replacing all established media together because the biological filter depends on its bacterial population.

Use a repeatable weekly check

1. Measure temperature, ammonia, nitrite, nitrate and pH.
2. Compare nitrate with the source-water baseline.
3. Observe every fish swimming and feeding before maintenance.
4. Change 25% of the water and condition the replacement water.
5. Inspect filter flow and rinse media only when needed.
6. Record readings, maintenance and any behaviour change.

A settled guppy should swim steadily, breathe regularly, hold open undamaged fins and feed consistently. The RSPCA’s fish health guidance identifies hiding, clamped fins, surface gasping, unusual balance, spots, wounds and sudden appetite changes as warning signs rather than diagnoses.

If behaviour or appearance changes, test water immediately and inspect the filter, heater, recent maintenance, food and social interactions. Correct measured environmental problems and isolate safely where appropriate. Do not select salt, heat or medicine from one symptom because different problems can look similar.

For diagnosis or treatment, use the OATA fish-vet directory. Keep dated notes or photographs of changes so the pattern can be assessed accurately. Dedicated nets and siphons for an isolation aquarium reduce transfer between systems.

Receive, document and acclimatise the fish carefully

Prepare the mature aquarium before the delivery day. Confirm the filter is running and test temperature, ammonia and nitrite. Someone must be present to receive the parcel because live fish cannot be left unattended.

Follow the arrival sequence

1. Receive the parcel in person and start filming before it is opened. Show the sealed parcel and outer box.
2. Open it in one continuous take. Show the fish while it is still inside the sealed bag before anything is disturbed.
3. Float the bag for 20–30 minutes before releasing the fish. This is Tropical Fish Co’s acclimatisation timing.
4. Inspect the fish the same day. Keep the continuous video and order number.

The current delivery and Live Arrival Guarantee policy explains the receiving and reporting process. Fish are hand-bagged in pure oxygen, placed in an insulated box and carried by a licensed live-animal courier; a heat pack is used when the weather calls for it. Tracking and the confirmed delivery date are sent by email.

If anything has gone wrong, contact us the same day with the order number and continuous unboxing video. The recording must begin with the parcel sealed, show it being opened and show the fish still in the sealed bag.

Use a biosecure quarantine system. The MSD Veterinary Manual recommends at least 30 days in a biosecure quarantine system, with longer isolation where indicated. Use dedicated equipment, biologically supported filtration and repeated water tests. Quarantine must still provide the same suitable temperature, pH, hardness and social-welfare planning as the main aquarium.

Screen every potential companion before mixing fish

A Green Cobra Female Guppy is peaceful and can live in a quiet community after the complete plan has been screened. Seriously Fish says it does well in a quiet community tank with other livebearers, rasboras, corydoras, small loricariids and tetras. Those are kinds of fish to assess, not universal promises that every species or individual will fit.

Avoid fin-nipping species. Seriously Fish specifically names tiger barbs and serpae tetras, while OATA says guppies should not be kept with fish that may nip their fins. Avoid them even in a larger or planted aquarium.

Apply the compatibility screen

1. Confirm an overlap at 22–28°C, pH 7.0–8.0 and 9–18 dGH rather than using the edge of two different ranges.
2. Compare adult size and the full social group required by each species.
3. Check fin-nipping, territorial, courtship and feeding-competition risks.
4. Measure the usable footprint after both groups and their cover are included.
5. Watch whether every animal can reach food and refuge.
6. Keep a mature separation option ready if behaviour changes.

Compatibility remains conditional because individual behaviour, sex mix, existing livestock, layout and filtration all affect the outcome. Temperature overlap alone is not enough, and a peaceful label does not replace observation after introduction.

Protect fish and breeding lines through observation

Watch the community at feeding time and during ordinary swimming. A workable group allows every fish to feed, move through the aquarium and withdraw without being trapped. Persistent pursuit, torn fins, clamping, hiding or repeated missed meals requires a change to the plan.

First test ammonia, nitrite, nitrate, pH and temperature because water stress can alter behaviour. Then inspect flow, cover, feeding distribution and the location of each fish. If one individual still cannot rest or feed, use the prepared separation aquarium rather than waiting for visible injury.

Keep guppies and Endler’s livebearers distinct

Endler’s livebearer is Poecilia wingei, a separately described species. The formal species description and its current valid status in Eschmeyer’s Catalog of Fishes distinguish it from Poecilia reticulata. Keep documented lines apart because laboratory research cited in our guppy guide confirms that the two species can hybridise.

Do not use colour, body size or a trade label alone to identify descendants. A Green Cobra mother does not establish the sire or guarantee that fry belong to a documented line. Record parentage and house breeding groups separately before making lineage claims.

Answer common Green Cobra Female Guppy questions

How big does a Green Cobra Female Guppy get?

It reaches 5 cm standard length. Plan for that adult female size rather than the 3–4 cm dispatch size.

What size aquarium does Poecilia reticulata need?

Seriously Fish gives a 45 × 30 cm footprint and approximately 41 litres, while Tropical Fish Co uses a mature filtered aquarium at least 60 cm long for one small guppy group.

How many Green Cobra Female Guppies should I keep?

Keep five or more where capacity and the sex plan allow. FishBase gives a group of five or more, while OATA advises at least three guppies.

Is Poecilia reticulata suitable for beginners?

It can suit a prepared beginner and carries Tropical Fish Co’s easy rating, provided the aquarium is mature, filtered and tested and the keeper maintains the social group and water-change routine.

What does a Green Cobra Female Guppy eat?

Feed an appropriately sized complete omnivore flake or granule as the staple, with safe invertebrate and algal variety. OATA advises one daily portion eaten within a few minutes.

What temperature and pH does Poecilia reticulata need?

Keep it at 22–28°C and pH 7.0–8.0, with 9–18 dGH. These values are the overlap of the Tropical Fish Co routine range with FishBase, Seriously Fish and OATA.

Is it aggressive or likely to nip fins?

It is a very peaceful fish. Avoid fin-nipping companions such as tiger barbs and serpae tetras, and intervene if persistent pursuit or fin damage occurs within the community.

Which kinds of fish can it live with?

Seriously Fish names other livebearers, rasboras, corydoras, small loricariids and tetras for a quiet community. Screen each exact species for shared water, adult size, group needs, feeding and behaviour.

How does it arrive alive in the UK?

Tropical Fish Co hand-bags the fish in pure oxygen, uses an insulated box and a heat pack when the weather calls for it, and sends it with a licensed live-animal courier. Receive it in person, start filming before opening the sealed parcel, show the fish in the sealed bag, then float the bag for 20–30 minutes before release.

References for identity, care and welfare

• FishBase: Poecilia reticulata — family, native range, recorded environment, biology, female length and aquarium group guidance.
• Seriously Fish: Poecilia reticulata — aquarium footprint, water ranges, diet, behaviour, compatibility and sexual dimorphism.
• OATA: How to look after guppies and mollies — group care, water quality, feeding and maintenance.
• RSPCA: Aquarium environment — biological filtration and waste processing.
• RSPCA: Fish health and welfare — normal behaviour, warning signs and health escalation.
• MSD Veterinary Manual: Management of aquarium fish — biosecure quarantine and water-quality-led assessment.
• OATA: Find a fish vet — UK fish-vet directory.
• Eschmeyer’s Catalog of Fishes: Poecilia reticulata — accepted scientific name.
• Description of Poecilia wingei — formal distinction from Poecilia reticulata.
• Eschmeyer’s Catalog of Fishes: Poecilia wingei — current valid species status.